Volcanoes made from the accumulated heat of some where under Earth’s crust that creates Magma and gas in that area and incurred pressure and high heat so it will erupt. When the magma under Earth’s crust breaks through to the surface, it creates a volcano. Usual form at plate boundaries
Mostly the volcanoes will be incurred where the crust is the weakest or we call the Ring of Fire such as in Indonesia , Philippines , Japan , South Korea etc.